drm/rockchip: Set IRQ_NOAUTOEN flag before requesting the interrupt

Calling request_irq() followed by disable_irq() is usually a bad idea,
specially if the interrupt can be pending, and you're not yet in a
position to handle it.

This is exactly what happens on my kevin system when rebooting in a
second kernel using kexec: Some interrupt is left pending from
the previous kernel, and we take it too early, before disable_irq()
could do anything.

A better way of ensuring safety is to set the IRQ_NOAUTOEN flag
on the irq before requesting it.

Cc: stable@vger.kernel.org
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>